An audio amplifier may comprise a power amplifier and e.g. a power supply unit. For some years, some audio amplifiers have also been equipped with signal processing units known as digital signal processors (DSPs). Demands on the possible output power of audio amplifiers for professional use are increasing. Audio signals may be pulsed, and may have high peak values with a simultaneously relatively low RMS value. As a result, high powers demanded from audio amplifiers may merely be needed for a relatively short time. This property is taken into account when designing power electronics assemblies for an audio amplifier, and said power electronics assemblies are thus able to deliver high voltages and currents on a short-term basis. On a permanent basis, these high powers may overtax the power electronics assemblies, which can be destroyed on account of overheating, for example. A current supply line is normally protected from overload by a circuit breaker, which may disconnect the supply of current and hence the audio amplifier in the event of excessive loading.
In order to inhibit the power electronics assemblies of an audio amplifier from being destroyed, it may be useful to provide for power to be reduced in the course of operation when the power becomes excessive. This may be accomplished by using power supply units in which the output voltage falls under load. This may decrease the supply voltage for the power amplifier, and the maximum output voltage of the power amplifier may be reduced.
However, a disadvantage in this case may be that the power reduction may affect the tonal properties of the audio amplifier, specifically depending on the load-dependent power supply unit used. A further disadvantage may be that merely specific load-dependent power supply units matched to the characteristics of the amplifier may be used.